Self-locking mechanism for tilting top drafting tables



July 29, 1952 E. LAXO 2,605,156

SELF-LOCKING MECHANISM FOR TILTING TOP DRAFTING TABLES Filed June 5, 19.50

HllllllllllllllllIIHIHl I I l I I Patented July 29, 1952 UNITED STATES PA EN OFFICE SELF-LOCKING MECHANISM FOR TILTING A TOP DRAFTING TABLES:

Ed Laxo, Oakland, Calif.

Application June 3,

7 Claims.

This invention relates to improvements in tilt adjustments of drafting tables and provides a quick-acting self-locking apparatus by which a drafting table can be adjusted to any desired inclination by merely gripping an operating lever and the table simultaneously and manually adjusting the table to the desired angle and releasing the operating lever Which when released automatically locks the table in the instant adjusted position.

This invention is an improvement over the table tilting arrangement disclosed in my copending application Serial Number 70,089, filed J anuary 10, 1949, because of its simplicity in design and arrangement and the method of operation and more secure locking.

This invention provides a drafting table which maybe adjusted at will to any desired angularity, from level to almost vertical so as to function as an easel if desired as Well as to provide easy access to all parts of the board when large drawings are executed, and which adjustment can be executed almost instantly.

The objects and advantages of the invention are as follows:

First, to provide a drafting board which can be adjusted to any desired degree of angularity from level to substantially vertical at will.

Second, to provide a drafting board as outlined which will maintain a level position transversely irrespective of such angular adjustments.

'I'hird,to provide angular adjusting means for a drafting board including a manually operable release lever for releasing the locking means and which automatically locks the drafting board in the instant angularly adjusted position when the release lever is released.

Fourth, to provide angular adjusting means as outlined which is relatively simple in construction, instantly operable, and positive in action, and which is composed of a minimum number of parts for efficient operation.

In describing the invention reference will be had to the accompanying drawings, in which:

Fig. 1 is a fragmentary side elevation of a drafting board with the invention applied thereto.

Fig. 2 is a rear elevation viewed in the direction 2-2 of Fig. 1 and shown on an enlarged scale with parts shown in section.

Fig. 3 is a section taken on line 3-3 of Fig. 2.

Fig. 4 is a section taken on line 44 of Fig. 2.

Fig. 5 is a section taken on line 55 of Fig. 1.

The invention includes a supporting structure 'lll having standards II which may be fixed or may be adjustable vertically (as disclosed in the 1950, Serial No. 165,951

previously mentioned copending application and which adjustment does not constitute a part of the present invention).

Fixedly secured to the upper end of each standard is one element of the locking device, being secured at two points as indicated at 12 and I3, the upper securing means l2 being indicated as a bolt, though it may be secured by any other suitable means, while the lower securing means consists of a bolt which terminates at one end in a long cylindrical head I 4 to function as a pivot and having a shoulder 15 to seat on the one element of the locking device which is secured to the standard by the nut Hi, this one element of the locking device consisting of a flat disc segment l1 one edge of which is coincident with one side of the standard as indicated at 18, the other side being formed to substantially a semi-circle as indicated at [9 to permit adjustment close to a right angle and being formed of flat steel plate or other suitable material.

The drafting board supporting frame is supported on the pivots l4, through a bushing 2| which assures uniform action without binding or play which might occur if supported directly on the wood. Thus the supporting frame will rock in either direction on these pivots.

The means for locking the board in any adjusted position consists of a clamp 22 for each end of the frame as indicated at 23 and 24, each consisting of a flat metal strip with a fulcrum 25 secured in one end and having a plug end 26 to fit in a hole 21 provided in the frame, with the other end bearing on the disc element as indicated at 28. A tapped hole 29 is provided adjacent the other end for the clamping screw, the tapped holes in the two clamps having respectively right and left hand threads.

A bushing 30 is mounted in each frame member in axial alignment with the threaded hole in the clamp member and has a length greater than the thickness through the frame member 20 so as to amply clear the inside of the frame member as indicated at 3| so as to assure positive clamping action irrespective of any swelling of the wood.

The actuating means operates on the order of a double end socket wrench and consists of a shaft 32 which has a socket 33 fixed on each end with the end of the shaft terminating in spaced relation inwardly from the end of the socket as indicated at 34, leaving ample space with clearance to the end for the head 35 of a screw 36 which operates in the tapped hole 29 in the clamp, A'washer 31 is interposed between-the "55 head of the boltand the bushing 30, the bolts respectively having right and left hand threads, the socket having projections 38 to prevent relative rotation of the washer.

Mounted on the shaft are two bell crank levers 39 and 40, with tension springs 4! having their respective ends 42 and 43 connected respectively to the arms 44 and 45 of the main lever, and to suitable fastening means 46 and 41 provided on the board supporting: frame or onithe drawing board as shown; the other arm of each bellcrank lever consisting of a socket 49 in which the respective ends 50 of the U-shaped control lever '5! are secured as indicated at 52, thecross. barv of this lever projecting substantially'to the front and extending throughout the major'portion of' the length of the table for simultaneous 'gripping of the front of the drawing table and. the. cross bar.

As will be noted, the board supporting frame is free to swing about the pivots l4 and the clamp 23 moves with this frame, skirting the circular portion of the disc, I]. When. thelever BI is released, the springs 4| turn the. shaft 32,which in turn, through the sockets 33 turn'the bolts 36, screwing them into the clamp and drawing the clamp against the 'disc' to lock the disc in the instant position. i

To adjust the drawing board to any specific angle, the lever'5l is lifted and brought up to the board to the position indicated at 5| where the board and the lever can be simultaneously grasped by one hand to retain the board free for adjustment and for manual 'urgenceof the board to thedesired angle, at which time the lever is merely released, the springs snapping 'it" down assisted by the weight of thelever to the dotted position indicated at El"; and tightening the clamps. Thus the apparatus isself-locking, by merely releasing the lever and whichcan be done without releasing the 'grip on. the board.

I claim:

1. A drawing table'having standards and a frame pivotally supportedby said standards 'on a horizontal axis and manuallyadjustable to any desired inclination at; will; locking means for locking said frame in adjusted ,positioncomprising; clamping 'r'ne'ans cooperative between said standards. and said frame andincluding each a clamp element; respectiverightand left hand screws cooperative with saidcl'amp. elements; a double ended. socket wrench cooperating with said screws; springmeanscooperative between said socketwrench and said frame for urging said socket wrench for tightening saidscrews insaid clamp elements, and a manually operable lever for releasing said screws and the clamp elements controlled thereby against theurg'enceiof said spring means, with said spring means locking said clamp elements when said lever is released.

2. A structure as. defined. in claim '1; said clamping means comprising a disc segment fixed on each standard; .said clamp elements having one end engaging .over the edge of said-discsegments and a fulcrum at ,theother end-with said screws operating in .tapped'boresprovided closely adjacent to and with the screws clearing the edge of the disc.

3. Self-locking means for a. drawing .tablehaving aframeand standards having pivotal means for supporting said frame, comprising; .a substantially semi-circularIplatefixed to each standard; a clamp having one end engaging said-plate and having a fulcrum at the otherlend engaged in .the.fra me,and having,a threaded :bore formed adjacent to and clearing thefperipheral edgeof the plate; a screw for each clamp; a double ended socket wrench cooperating with said screws; spring means for urging said socket wrench to tighten said screws in said clamps; and a manually operable lever fixed on said shaft for loosening said screws to release the clamp with said spring means tightening said screws when said lever is released.

4. Self-locking means for adrawing table having standards and a frame pivotally supported by said standards on a horizontal axis comprising; a substantially semi-circular plate fixed to each standard and having their axes coincident with the pivotal support for the frame; a clamp for each plate and having one end cooperating with the edge'portion of the plate and having a fulcrumat the other end, and each provided with a tapped bore adjacent to and clearing the edge of theplate; a screw for each clamp and having a head; a bushing for each screw and having a in saidframe; a washer interposed between the length" greaterthan' the thickness of and mounted headof each screw and its bushing; a shaft having a socket at each end'and engaging the heads of the respective screws and including means retaining said washers against relative rotation with said heads slidable and nonarotatable' in said sockets; a spring lever on said'shaft adjacent each socket'and'a spring cooperating betweeneach lever and said frame; and a U- shaped manually operable lever having its *respective legs fixedin the respective spring levers and with its cross bar projecting substantially to the front of and'extendingthroughout the major portion of the length of the drawing table when in damp releasing position for simultaneous gripping. of the lever with 'thefcl'amps released, and of the table for angular adjustment, with said springs operating said'screws 'to clamp the table 'in adjusted position when the manually operable lever is released. v

5. An automatically adjustable tilting drafting table comprising a pair of spaced, vertical, stationary frame members; a drafting board; means pivotally mounting the drafting board on the frame members for swinging about a horizontal axis; a clamping member for each frame member, eachsaid clamping 'member'beingfixed to the drafting board; a screw member forand in threaded engagement with 'each' clamping member, said screw members being oppositely threaded and being operablewhen rotated in one direction, to clamp'the clamping -members' to the frame members and, when rotated in the Opposite direction, to release the clamping members from the frame members to allow. rotation of the drafting board. 7

6. An automatically adjustable, tilting draft ing table comprising'a pair of spaced upright stationary frame members; a drafting. board; means pivotally mounting the draftihgb'oar'd .on the frame members forswinging about'a'horizontal axis; a clampingm'ember, for-each frame member, said clamping members being fixed to the draftingboard onopposite sides thereof for cooperation with the frame members; Ta" screw member for each clamping member, one of i said screw members having aleft-handithread-and the other having a right-hand thread, each said screw member being in threaded engagement with its clamping member, said screw members being arranged. in axial alignment with-one-another'; a .shaft extending between and fixed to said screw membersto rotatetthe same; means for irotatingl-said shaft-=manually; and spring means fixed at one end to the shaft and at the other end to said drafting board to rotate said shaft in a direction to clamp said clamping members to the frame members.

7. An automatically adjustable, tilting drafting table comprising a pair of spaced, upright stationary frame members; a drafting board; spaced, depending members fixed to the drafting board on opposite sides thereof; means pivotally mounting the depending members on the frame members for swinging the drafting board about a horizontal axis; a plate interposed between each depending member and the adjacent frame member; a clamp for each of said clamp the clamping members to said plates when rotated in one direction and to release the same from said plates when rotated in the opposite REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 522,598 Jones July 10, 1894 922,565 Cole May 25, 1909 1,359,399 Lewis Nov. 16, 1920 1,373,473 Weydell Apr. 5, 1921 1,956,546 Froelich Apr. 24, 1934 2,312,636 Froelich Mar. 2, 1943 2,356,924 Froelich Aug. 29, 1944 2,452,216 Yarber Oct. 16, 1948 

